Helmet strap



FIG. 1 is a front perspective view of a helmet strap showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is an enlarged end view thereof; and,

FIG. 5 is a rear view thereof. 

CLAIM We claim the ornamental design for a helmet strap, as shown and described. 